Here is the full list of all 42 Knights of Pen and Paper +1 achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Finish the storyline as fast as you can (less than 365 days but you may extend that to 465).
Complete a campaign using all 5 Game Developers as characters.
Clear 50 dungeons.
Play with all characters in game.
Clear 10 dungeons.
Buy all goodies in game.
Visit your Kitchen inside the game.
Unlock all masters.
Finished the campaign.
Continue the game after a game over.
Visit every single place in game.
Choose a weird combination of character and class.
Play with all classes in game.
Buy the highest weapon upgrade available.
Kill a dragon.
We know it may be frustrating to die so we've just rewarded you with this achievement. Do not give up, the game is about to begin!
Use a potion while full health.
Buy the highest armor upgrade available.
Unlock a new master.
Reach Level 30 in every character of your group.
Unlock the Shaman class.
Reach Level 30 in a trio.
Reach Level 30 in any character.
Unlock the Necromancer class.
Spend 9.001 golds.
Reach Level 15 in a specific Spell.
Earn 9.001 golds.
Unlock the Barbarian class.
Unlock the Knight class.
Unlock the Game Developers that made the game.
Reach Level 15 in any character.
Clear a dungeon.
Unlock the Hunter class.
Gather 10 grindstones from veins.
Win a battle with 7 monsters.
Unlock the Bard class.
Gather a grindstone by mining veins.
Make the blacksmith dance.
Roll 1 in any random roll.
Roll 20 in any random roll.
Reach Level 5 in any character.
Kill an elite minion.